Durability of carbon fiber reinforced polymer (CFRP) pretensioned elementsunder tidal/thermal cycles

This paper presents results from an experimental study to assess the likely effect of diurnal/seasonal temperature change on the durability of carbon fiber reinforced polymer (CFRP) pretensioned piles driven in tidal waters. Twelve precracked CFRP pretensioned beams designed to fail by rupture of th e prestressing rods were kept outdoors in two salt water tanks and simultan eously subjected to wet/dry cycles (simulating tides) and hot/cold cycles ( simulating temperature variation). Durability was assessed from flexure tes ts conducted periodically over the nearly 3-year exposure period. The resul ts of the tests indicated that durability was largely unaffected, although both bond degradation and reductions in ultimate capacity were observed in some of the exposed specimens. Degradation appeared to be linked to the ext ent of precracking damage sustained prior to exposure. This suggests that w hen CFRP pretensioned piles are used, driving stresses should be carefully monitored to minimize damage.